Improvement in valves for steam-engines



PATENT OFFICE.

SMITH GROOM, OF TROY, NEW YORK.

Specification forming part of Letters Patent No. 43,402, dated July 5, 1864.

To all whom it may concern Be it known that I, SMITH GROOM, of the city of Troy, in the county of Rensselaer and State of New York, have invented a new and useful Improvement in Slide-Valves of Steam-Engines and I do hereby declare that the following is a full, clear, and exact description of the construction and operation of the same, reference being had to the annexed drawings, making a part of this specification, in whichvalve reversed or turned downside up, for the purpose of showing more perspicuously the various cavities or chambers therein and their relation to each other. Fig. 2 represents in perspective the interior of the steam-chest, the top plate, and also one end and one side thereof, being left oft' for the purpose of a better view, and also represents the slide-valve right side up and in position for working, one cylinder-port, together with the exhaust-port, being covered thereby, the other cylinderport, Z, being uncovered by said slide-valve. Fig. 3 represents a transverse section of said steam-chest and `slide-valve, showing the relative position of the slide-valve chambers a a, together with their respective ports c c and the exhaust-chamber L, the exhaustport M, also a section of the steam-supply pipe X. Fig. 4 represents in perspective a View ofthe exterior of the steam-chest as put together, X representing a section ofthe steamsupply pipe at the top, connecting said steamchest with the boiler, Z representing a portion of one of the cylinder-passages connecting the cylinder with its respective port in the steam-chest, Y representing the bearing or or aperture through which the slide-valve rod reciprocal] y moves.

The same letters represent like parts in each figure. y

I make the steam-chest with its exhaustport and connections, also its cylinder-ports and respective connections, also its steamsupply pipe connecting said steam-chest with the boiler, as are the corresponding parts in other steam-chests commonly in use.

rlhe rod that communicates motion to the slide-valve is attached thereto at the vertical seat N, Fig. 2. The steam-chest I make so much wider in proportion to its length than others commonly in use as will allow a slidevalve to operate therein, having two counterbalance chambers, a a, Figs. l, 2, 3, hereinafter described. I make'said slide-valve, Figs. l, 2, 3, having a cavity or chamber, L, on the under side thereof, of sufcient capacity so as to freely pass oft' the exhaust-steamfrom the cylinder through the exhaust-port M in the floor of said steam-chest, directly beneath and covered by said slide-valve chamber L, said last-named chamber being so madeas that a margin of sufficient width shall remain around Figure 1 represents in perspective the slidethe periphery thereof as effectually to shut oft' from said chamber L direct communication with the steam in the steam-chest. Said chamber L is of sufficient length and breadth as only to cover at one and the same time the exhaust-portM and also one cylinder-port; and thus, While the steam in the steam-chest is passing through the cylinder-port Z, Fig. 2, into one end of the cylinder, the exhaust-steam from the other end of the cylinder passes through the other cylinder-port into the chamber L, and thence 'out through the exhaust-port M, Fig. 3, and Y vice versa, when the said slidevalve shall recede to the other extreme and cover the'other cylinder-port, Z. Notches P l? are made on the opposite edges of said slidevalve, Figs. 1 and 2, and correspond as to length with the cylinder-ports, respectively, for the purpose of reducing the surface of the slide-valve at or near the chamber L, subjected to pressure by the steam. These notches may be omitted at my option. I make two chambers or recesses, a a, Figs. l and 3, on the under side of said slide-valve-one on each side of said exhaust chamber L-each chamber a a having through the dome or upper part thereof a port, c c, through which the steam of the steam-chest passes freely and continuously into said chambers a a, respectively, each of last aforesaid chambers also having a margin around their periphery of sufficient width as effeetually to shut oft' all communication with or escape of steam therefrom into the exhaust-chamber L. Consequently the pressure of steam within these chambers a a. counterbalance in part the downward pressure of the steam in the steam-chamber against the upper surface of said slide-valve7 the steam in said chambers a a acting also as cushions, and at the same time lubricating the bearings of said slide-valve, essentially lessen the friction and consequent wear of the bearings of the 

